What
Is Serotonin Syndrome?

Serotonin syndrome is a potentially serious drug interaction. It
occurs when too much serotonin builds up in your body. Nerve cells normally
produce serotonin. It’s a neurotransmitter, which is a chemical. It helps
regulate:

digestion

blood flow

body temperature

breathing

It also plays an important role in the proper functioning of
nerve and brain cells.

If you take different prescribed medicines that treat depression,
migraine headaches, and manage pain together, you may end up with too much
serotonin in your body. Too much serotonin can cause a variety of mild to
severe symptoms. These symptoms can affect the brain, muscles, and other parts
of the body.

Serotonin syndrome typically occurs when you start a new
medication. It can also occur if you increase the dosage of a medication you’re
already taking. The condition is most likely to occur when two or more drugs
are taken together. Serotonin syndrome can be fatal if you don’t receive prompt
treatment.

What
Are the Symptoms of Serotonin Syndrome?

You may have symptoms within minutes or hours of taking a new
medication or increasing the dose of a medication. The symptoms may include:

confusion

disorientation

irritability

anxiety

muscle spasms

muscle rigidity

tremors

shivering

diarrhea

rapid heartbeat, or tachycardia

high blood pressure

nausea

hallucinations

overactive reflexes, or hyperreflexia

dilated pupils

In more severe cases, the symptoms may include:

unresponsiveness

a coma

seizures

an irregular heartbeat

What
Are the Causes of Serotonin Syndrome?

Typically, the condition occurs when you combine two or more
medications, illicit drugs, or nutritional supplements that increase serotonin
levels. For example, you might take medicine to help with a migraine after
already taking an antidepressant. Certain types of prescription medications,
such as antibiotics, antivirals used to treat HIV and AIDS, and some
prescription medicines for nausea and pain may also increase serotonin levels.

Examples of drugs and supplements associated with serotonin syndrome
include:

Antidepressants

Antidepressants associated with serotonin syndrome include:

selective
serotonin reuptake inhibitors (SSRIs), such as Celexa and
Zoloft

serotonin and norepinephrine reuptake inhibitors
(SNRIs), such as Effexor

Herbal Supplements

Cold and Cough Medications

Certain over-the-counter cold and cough medications that contain
dextromethorphan are associated with serotonin syndrome. These include:

Robitussin DM

Delsym

How
Is Serotonin Syndrome Diagnosed?

There’s no specific laboratory test for serotonin syndrome. Your
doctor may begin by reviewing your medical history and symptoms. Be sure to
tell your doctor if you’re taking any medications or have used illegal drugs in
recent weeks. This information can help your doctor make a more accurate
diagnosis.

Your doctor will usually perform several other tests. These will help
your doctor find out if certain organs or body functions have been affected.
They can also help your doctor rule out other conditions.

Some conditions have similar symptoms to serotonin syndrome.
These include infections, drug overdose, and hormonal problems. A condition
known as neuroleptic malignant syndrome also has similar symptoms. It’s an
adverse reaction to medications used to treat psychotic diseases.

Tests your doctor may order include:

a complete blood count (CBC)

a blood culture

thyroid function tests

drug screens

kidney function tests

liver function tests

What
Are the Treatments for Serotonin Syndrome?

If you have a very mild case of serotonin syndrome, your doctor
may only advise you to stop taking the medication causing the problem
immediately.

If you have severe symptoms, you’ll need to go to the hospital.
At the hospital, your doctor will closely monitor your condition. You might
also receive the following treatments:

withdrawal of any medication that caused the
condition

intravenous fluids for dehydration and fever

medications that help relieve muscle stiffness
or agitation

medications that block serotonin, such as
Periactin (cyproheptadine)

What
Are the Complications Associated with Serotonin Syndrome?

Severe muscle spasms can lead to a breakdown of muscle tissue.
The breakdown of this tissue can lead to severe kidney damage. The hospital may
need to use medications that temporarily paralyze your muscles to prevent
further damage. A breathing tube and respirator will help you breathe.

What
Is the Long-Term Outlook?

The outlook is very good with treatment. There are typically no
further problems once serotonin levels return to normal. However, serotonin
syndrome can be fatal if it’s not treated.

How
Can I Prevent Serotonin Syndrome?

You can’t always prevent serotonin syndrome. Make sure your doctor
knows what medications you’re taking. Your doctor should closely monitor you if
you’re taking a combination of medications known to increase serotonin levels.
This is especially important right after you start a new medication or right
after you increase your dosage.

The FDA requires warning labels on products to warn patients of
the risk of serotonin syndrome.